Synchronization tester



Aug. 5, 1947 A. BOHANNON 2,425,081

SYNCHRONIZAT ION TESTER Filed Sept. 24, 1945 INVENTOR.

WILLRAM A. BOHANNON ATTORNEY.

Patented Aug. 5, 1947 UNITED SYNCHRONIZATION TESTER William A. Bohannon, Uniondale, N. Y., assignor to Republic Aviation Corporation, a corporation of Delaware Application September 24, 1943, Serial No. 503,603

1 Claim. 1

This invention relates to synchronization testers and contemplates a tester which will accurately indicate the synchronization or the non-synchronization of the contacts or breakers of the magnetos of dual ignition systems for internal combustion engines. While the present invention may be of general application and use, it is essentially designed for testing the synchronization of thedual ignition systems of the internal combustion engines used in aircraft, particularly high altitude aircraft.

This invention contemplates a tester having a visual indicator for each of the magnetos of a dual ignition system, whereby the operation of the several indicators may be concurrently and accurately observed to determine the degree of variance in, or the simultaneous operation of, the contacts or breakers of the several magnetos of the system.

With the above and other objects in view, as will be apparent, the invention consists in the construction, combination and arrangement of parts, all as hereinafter more fully described, claimed and illustrated in the accompanying drawings, wherein- Fig. 1 is a diagrammatiqview of the present invention showing the electrical circuits used with 110 volt current and a transformer;

Fig. 2 is a similar view illustrating the same used with a battery; and

Fig. 3 is an elevation of a tester involving one or the other of the circuits illustrated diagrammatically in Figs. 1 and 2.

In alrcraft it is customary to employ dual ignition systems adjusted to operate in perfect synchronization, each system having a magneto connected with a spark plug in each of the engine's cylinders, the make and break of the magneto constituting the timer of the system and the distributor determining the order of the successive firing of the several cylinders. These dual systems, where each cylinder is provided with two spark plugs, must operate in perfect synchronization in order to get the maximum ignition spark at or near the approximate end of the compression stroke of the piston. If one spark plug or series of spark plugs lags in firing, there is an appreciable loss of power particularly at high altitude where operating conditions at best are diiilcult, and not infrequently there is a complete failure of ignition in one or more cylinders where the two sparks instead of being simultaneously produced are created in a sequence. Thus an instrument which accurately and instantly indicates the lag, if any, in the closing and opening of the magneto contacts or breakers; is of inestimable value in the adjustment of'the ignition system prior to flight.

,Heretofore instruments for the testing of the synchronization of dual ignition systems have employed testing lamp circuits fed by a battery or in. series with the secondary winding of a transformer, each circuit also including the movable contacts or breakers of one of the magnetos. In this manner each magneto acts as a switch to light the lamp of its test circuit when the contacts or breakers of the magneto close and to extinguish said lamp when the contacts or breakers of the magneto open. Thus, in this prio instrument, when the magnetos are operating in perfect synchronization, the two lamps of the instrument light and extinguish simultaneously, but if one magneto is lagging the lamps of the test circuits extinguish in sequence or succession.

Since the charge 01' the engine is fired when the contacts or breakers of the magnetos open, precise testing is predicated upon the opening of the contacts or breakers and when this occurs the lamps of the prior type of tester extinguish. With these prior testing instruments, especially when operating in conjunction with engines requiring substantially perfect synchronization, it is particularly difllcult to observe the several test lamps to ascertain the simultaneous or successive extinguishing thereof with any degree of certainty. In bright light such as daylight, it is extremely diflicult, if not altogether impossible, to precisely ascertain either the simultaneous or the successive extinguishment of the lamps and frequently the observer has the illusion that both lamps are lighted when in fact one of them is extinguished.

The elimination of the ditliculty of detecting the simultaneous or the successive extinguishment of the several test lamps, and the minimizing, if not total elimination, of any inaccuracy in the test normally attributable to the usual optical illusion in observing light is contemplated by this invention.

It has been found by experiment that the human eye will more accurately and precisely react to and record the lighting of a lamp than the extinguishment thereof and therefore the present invention proposes the lighting of test lamps when the contacts or breakers of the magnctos open and the extinguishinent of the lamps when the contacts or breakers of the magnetos close.

The instant invention also contemplates the protection of the battery or transformer, as the case may be, from short circuiting or burning due to the making and breakingof the test circuits forming part hereof.

Reference being had more particularly to the drawings, A represents a casing or housing designed to include all of the circuits and elements combining to create the present tester. At one end of theicasingg or housingzAe are-lthes leads; In and Ii. by. which the instrumenmmaiv bed-13011: nected to the usual 110 volt power line or other source of electrical energy. These leads within: the housing A are connected to the primary winding I2 of a standard transformer.

The secondary Winding l3.otrthe,tran sinrmsn is electrically connected by thBgliIlQglr-bh-LQH-Eh. the resistance 3i to the terminal IE on the exterior of the housing. The opposite end tbs. secondary winding I3 of the transformer'iscomnected by the line I5 through the resisiance-Wr to the terminal I'I also. on the exterior of the housing; Centrally. of. its: lengththat Secondary winding I3 of. the; transformer. is connected by, the Wire l a-znlthroughtheswitchcls toaqground terminal. 2;l on the exterior otthe housing.

A. lamp. 2B. is. connected; in. parallel with.the line.- IA on one. side and.tl'ie. ground. wire Ill-2.0 on theother side. Asimiiarlamp. 3.01s connected in parallel. between the gmundmine I.8.' -2fl.a1nd theline I5. Asis apparentfrein Rig. 3;the1amp are. visible from the exterior of. the housing A andtne switch. [9. is operable from the. exterior of. the. housing.

Inpractlce tlieterminals. lijandl l1 re respectively connected to. the contacts. 22. and 25" of the magnetos B; and. B', the movable contacts 23' and 26 of which are connected through the wires 24 and 21 to ground. The central or common. terminal 2| is directly connected to ground by the wire 28. Hence it will be; manifest that in that form of the invention disclosed in Figs. 1 and 3, the connecting of the terminals I6, I] and 21 as above described and the closingof the switch I9 will set the device for the testing of the. synchronization of operating ofthe two magnetos B and B. The contacts 22 and 23' and 25 and 26 respectively of" the magnetosB and B are shown out of engagement: in Fig- 1. When this conditionexists and the switch; It, is closed, current from the secondary 001113 of thetransformer will flow through wires M. i8, and I5 and through lamps 29 and. 30: The continued rotation of the: magnetos B and Bf closes the contacts 22-23 and -26. thereoflthereby directing the current flow from the secondary coil iii of the transformer through. the common ground wire-s I8-2Il. terminal 2| and. wire 28 to ground and through the lines It and I5, the terminals I6 and II, the closed contacts 22-23 and 25-26 aforesaid and through the wires 24 and 21 to ground. When this occurs the lamps 23 and 3B are shunted and are consequently extingu shed.

When the contacts are opened. as illustrated n Fi l, the current. being unable to flow through the magneto contacts or breakers. is directed through the lamps 29 and 30, lighting them. Titus the lamps 29 and 30 become illuminated when vlie breakers or contacts of the magnetos :u out. of engagement and become extinguished when the breakers or contacts of the magnetos are in engagement.

Vvlicn the Icntnrls 22-23 are open and the contacts 25-25 are closed, the current induced in His secondary i3 flows simultaneously in the ShOl'tcl' circuit i l. 3!, 29, i8 0f the magneto B 4 and the longer circuit I5, 32, II, 25-25, 21, ground, 28, 2|, 2!], I8 of the magneto B leaving thus the lamp 3!) shunted and consequently extinguished. Obviously it is lamp 25 which is shunted when inversely the contacts 22-23 are closed and the contacts 25-26 are open.

Fig. 2 illustrates the present invention as it is modifiedfor operation from abgttary 33. In this. embcsiimente one siderof the; battery 33 is connected to ground and the other side by a lead 34; through the switch I9 to a pair of lines I4 and I5. The line I4 connects through the resistance- 3% to the line I4 leading from the housiIJgAfizuL-ending; in the terminal IS. The line I5.- connectsthrough the resistance 32 to the line;I.-5,-em:l,1' 1. 1g extcriorly of the housing in the terminal I1. The lamps 29 and 30 respectively are connected to the lines I4 and I5 and to the common ground wire 20' ending in the terminal 2I exteriorly of the housing to be connected by a wire 28 to ground.

Inthls modification of the invention the contacts 22-23 and 25-25 of the mag utos B; and B"*are illustrated as closed, as is also the switch It. thereby; directing current. from the battery 33" throughthe line I4. resistance 3i and line I43 the terminal I6, and contacts 22-23 to, gmundand also through the line I5". resistance 32', the line I5 through the terminal. I! and cone tacts 25-26 to ground; Under these conditions the lamps 28 and 30. are extinguished. When the contacts 22-23 and" 25-26 of the magnetos B-B" are opened, the current flow will be from the battery33-through the line I 4', line I-t the lamp-29 and the common ground wire 20' and also through the line I5, the line I5, the lamp 30 to the common ground wire 20', whereupon the lamps will each become illuminated the in; stant electrical engagement is broken between the contacts or breakers of the magneto with which it is cooperating;

When only either the contacts 22-23 or 25-26 are opened, the corresponding battery circuit is directed through the corresponding lamp 29 or 30; while the other lamp remains shunted.

From the foregoing it will be evident that; the present invention nwides a test lamp for each magneto of a dual ignition system and that each of these lamps will become illuminated the instant the contacts or breakers of its cooperating magneto break electrical engagement and will be extinguished when said contacts or breakers again enter into electrical engagement. Thus the close and accurate observation of both lamps at the same time will be facilitated in that sequential or' simultaneous illumination of the lamps 29 and 30 canbe truly observed and the breaker or c0ntacts of, the timers or magnetos adjusted.

After the tester has been connected with the installed magnetos as above described the engine is rotated slowly by hand, until the lamp 29 and 30 become illuminated. If this illumination occur simultaneously and at the proper point in the cycle of the engine, the magnetcs are prop erly synchronized: but if the lamps become illu minated in sequence or at an improper point in the cycle of the engine it denote that the mag netos are not operating in synchronization and/or that the firing is taking place at the incorrect point in the compression stroke. When adjustments have been made to Correct any inaccuracies in timing the test i repeated until the lamps 29 and 3!] become illuminated at exactly the same instant and at the proper pl'rdetel'mincd point in the cycleoi the engine.

The inventive concepts and several illustrative embodiments thereof having been thus disclosed in the manner required by the statutes, what is claimed as new is:

Apparatus for synchronizing the breaker points of magnetos, comprising a lamp associated with and individual to each magneto, a power source having a centertap and a switch in series with the centertap, a closed circuit for one lamp including part of the power source on one side of the centertap, the centertap and a currentlimiting means in series with the lamp, a closed circuit for the other lamp including a part of the power source on the other side of the centertap, the centertap and a current-limiting means in series with said latter lamp, and parallel shunting connections for each lamp including the breaker points of the associated magneto.

WILLIAM A. BOHAN NON REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 729,738 France May 2, 1932 

